Archery Bow Modular Cam System

ABSTRACT

A modular cam system for an archery bow or crossbow includes swappable cams that change the maximum draw weight of the archery bow or crossbow. Moreover, the modular cams can be affixed to a rotatable member in a number of orientations to set the desired draw length without changing the limbs, tightening or loosening limb bolts, or disassembling the bow. Further, the maximum draw weight of the bow remains substantially similar throughout a large portion of the draw length adjustment for a specified cam module.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application No.61/539,885, filed Sep. 27, 2011, the entire contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates generally to archery bows and more specificallyto compound bows having cam adjustability.

Various types of compounding archery bows are generally known in theart. Compounding archery bows generally include a plurality of rotatablemembers, at least one of which comprises a cam. The cam desirablyprovides for a reduction in the draw weight when the bow is fully drawn,allowing an archer to hold the bow in a drawn position with lessfatigue.

Some compounding bows include at least one rotatable member having acam, wherein at least a portion of the cam is either adjustable withrespect to the rest of the rotatable member or can be removed entirelyand replaced with another cam module having a different shape.

U.S. Pat. No. 4,461,267 teaches a bow wherein interchangeable moduleshaving different cam shapes are used to change the draw length of thebow. The bow's peak draw weight was determined solely by the spring rateor stiffness of the bows limbs, which were generally fixed in the bowhandle. The Bear Delta V bow, which embodied the invention of U.S. Pat.No. 4,461,267, was marketed in one of two different fixed draw weights.The draw length of the bow was determined by a cam module, whichrepresented one module from a set of modules that could be attached tothe rotatable member body.

U.S. Pat. No. 4,461,267 teaches that each of the available draw lengthmodules are very similar to one another through the initial portion ofthe draw length, until the draw force reaches its peak (represented bypoint “C” in FIG. 2 of U.S. Pat. No. 4,461,267). The various draw weightmodules result in the same peak draw weight with that draw weightdropping off more rapidly with each progressively shorter draw weightmodule.

One of the first patents to introduce draw length module cams mounted onthe ends of the bows limbs was U.S. Pat. No. 4,515,142. This patentbasically applied the teaching of the previous '267 patent to cams atthe bows limb tips rather than to cams mounted on pylons extending fromthe handle of the bow. In the '142 patent, it is taught that a main cambody can be designed such that it can accept individual modules that canbe designed to provide a specific draw weight and the draw length of thebow can be changed by interchanging a replaceable module. The main shortcoming of this concept is that each module only provides a single drawforce profile capability; therefore it would require a multitude ofdifferent designed modules to cover all of the normal draw weight anddraw length combinations encountered in market place.

Larry D. Miller's U.S. Pat. No. 4,519,374 teaches a modular cam conceptthat is similar to Nurney's '142 concept in that it requires a differentset of attached modules to provide a specific draw force profile.Miller's concept is intended to provide some of the same benefits as theNurney concept. However, the '374 concept is even more complex in thatit can require a number of add on plates or modules to arrive at asingle given draw force configuration.

U.S. Pat. No. 4,774,927 issued to Marlow Larson teaches a different typeof modular cam concept that is designed to provide variability in thelet-off performance of the bow. In particular, by adjusting the modules,the user can change the cam ratio of the bow in the segment of drawafter peak weight. In combination, by adjustment of the modules, theuser can select the ultimate draw length. Having selected the desiredlet-off (holding weight), the '927 concept offers the ability to makesmall incremental rotations of the module which in turn results in anincremental change in the bows draw length, as illustrated in FIGS. 11and 12 and explained in the body of the '927 patent. While this conceptrequires only one module on each cam that is not readily replaceable orsubject to loss, the resulting system is limited in that it does notoffer draw weight change capability.

Larson U.S. Pat. No. 5,678,529 is a continuation-in-part of a series ofpatents including the '927 patent. This patent is a variation on therotating module concept, emphasizing the design of a rotating modulethat is capable of maintaining somewhat consistent peak draw weightwhile being adjustable in six, not necessarily uniform, draw lengths.FIG. 21 and the corresponding table included in this patent shows someof the limitations of this concept, which is also somewhat complex.

Additionally, Published Application No. US 2010/0147276, listinginventors Dennis Wilson and Rex F. Darlington, discloses a “CompoundArcher Bow With Replaceable Draw Length Adjustment Modules”. Mr.Darlington has been a prolific inventor in the area of compound bow camdesign, and Publication No. 2010/0147276 embodies one of his latestconcepts utilizing replaceable modules. This Publication teaches the useof modules as a means to affect the draw length of the bow, with a givenmodule pair applied to the main cams in order to arrive at a specificdraw length.

U.S. Pat. No. 7,721,721, directed to a “Reversible and Adjustable ModuleSystem for Archery Bow”, teaches the use of interchangeable modules thatcan be attached to the main cam body. The concept is to provide thedealer with a single bow and provide that bow to an archer with a totalof eighteen selected values for draw weight and length.

All US patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

A brief abstract of the technical disclosure in the specification isprovided as well only for the purposes of complying with 37 C.F.R. 1.72.The abstract is not intended to be used for interpreting the scope ofthe claims.

BRIEF SUMMARY OF THE INVENTION

In some embodiments, an archery bow comprises a riser and opposed limbs,and each limb supports a rotatable member. At least one rotatable membercomprises a body and a cam module. The body defines a bowstring payouttrack and the cam module defines a power cable take-up track. The cammodule is adjustable with respect to the body between first and secondorientations. The draw length of the bow in the first orientation isdifferent from the draw length of the bow in said second orientation. Amaximum draw force of the bow in the first orientation is substantiallysimilar to a maximum draw force of said bow in said second orientation.In some embodiments, the bow has at least a 45% let-off draw force inboth the first and second orientations. In some embodiments, the cammodule is rotated at least 10 degrees with respect to the body betweenthe first and second orientations. In various embodiments, the cammodule is rotated at least 20, 30, 40 or 50 degrees with respect to thebody between the first and second orientations.

In some embodiments, the cam module is a first cam module of a firstsize and the bow further comprises a second cam module that is shapeddifferently from the first cam module. The first cam module can bereplaced with the second cam module. A maximum draw force of the bowusing the second cam module is greater than a maximum draw force of thebow using the first cam module. In some embodiments, the second cammodule is larger than the first cam module.

In some embodiments, the second cam module is adjustable with respect tothe body between first and second orientations. A draw length of the bowusing the second cam module in the first orientation is different from adraw length of the bow using the second cam module in the secondorientation. A draw force of the bow using the second cam module in thefirst orientation being substantially similar to a draw force of the bowusing the second cam module in the second orientation.

In some embodiments, an archery bow comprises a riser and opposed limbs,and each limb supports a rotatable member. At least one rotatable membercomprises a body and a cam module. The body defines a bowstring payouttrack and the cam module defines a power cable take-up track. The cammodule is adjustable with respect to the body between plurality oforientations including a maximum draw length orientation and a minimumdraw length orientation. A draw length of the bow in the maximum drawlength orientation is at least six inches greater than a draw length ofthe bow in the minimum draw length orientation. A draw force of the bowis substantially constant over at least 60% of the range ofadjustability between the maximum draw length orientation and theminimum draw length orientation. The archery bow has at least 45%let-off in draw force both the maximum and minimum draw lengthorientations.

In some embodiments, a draw length of the bow in the maximum draw lengthorientation is at least eight inches greater than a draw length of thebow in the minimum draw length orientation.

In some embodiments, a draw force of the bow is substantially constantover at least 75% of the range of adjustability between the maximum drawlength orientation and the minimum draw length orientation.

In some embodiments, a draw force of the bow is substantially constantover all of the range of adjustability between the maximum draw lengthorientation and the minimum draw length orientation.

In some embodiments, an archery bow comprises a riser and opposed limbs,and each limb supports a rotatable member. At least one rotatable membercomprises a body and a cam module. The body defines a bowstring payouttrack and the cam module defines a power cable take-up track. The cammodule is adjustable with respect to the body between first and secondorientations

In some embodiments, an archery bow comprises a riser and opposed limbs,and each limb supports a rotatable member. At least one rotatable membercomprises a body and a cam module. The body defines a bowstring payouttrack and the cam module defines a power cable take-up track. The cammodule is rotatably adjustable with respect to the body between firstand second orientations. The cam module is removable from the bowwithout precompressing the limbs or relaxing the tension on the limbs ofthe bow. In some embodiments, the cam module comprises a hook thatengages a portion of the rotatable member body. In some embodiments, thehook comprises a semi-circular portion that abuts a semi-circularportion of the rotatable member body.

In some embodiments, an archery bow kit comprises a riser and opposedlimbs. Each limb supports a rotatable member. At least one rotatablemember comprises a body and a first cam module. The body defines abowstring payout track and the first cam module defines a power cabletake-up track. The kit includes a second cam module that is suitable forreplacing the first cam module. Each of the cam modules comprise alet-off portion and a peak weight portion, the peak weight portion ofthe second cam module being larger than the peak weight portion of thefirst cam module. A peak draw force of the bow using the first cammodule is less than a peak draw force of the bow using the second cammodule, and the let-off portion of the first and the second cam moduleseach producing at least 45% let-off in draw force.

In some embodiments, a method comprises providing parts for an archerybow including at least one rotatable member body and a plurality of camweight modules. Each cam weight module is attachable to the rotatablemember in one of a plurality of orientations, wherein each orientationresults in a different draw length. Each cam weight module results in adifferent draw force and provides at least a 45% let-off in draw force.The method further comprises selecting a cam weight module based upon adesired draw force and assembling the parts to form the archery bow,including attaching the selected cam weight module to the rotatablemember body.

These and other embodiments which characterize the invention are pointedout with particularity in the claims annexed hereto and forming a parthereof. However, for a better understanding of the invention, itsadvantages and objectives obtained by its use, reference can be made tothe drawings which form a further part hereof and the accompanyingdescriptive matter, in which there are illustrated and described variousembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings.

FIG. 1 shows a side view of an embodiment of an archery bow in a bracecondition.

FIG. 2 shows an embodiment of a rotatable member.

FIGS. 3A-3D show embodiments of cam modules.

FIGS. 4A-4D show alternative embodiments of cam modules.

FIG. 5A shows a side view of an embodiment of an archery bow in a drawncondition.

FIG. 5B shows a detailed side view of the archery bow of FIG. 5A.

FIG. 6 shows draw force curves for an embodiment of a cam module atseveral different draw length orientations.

FIG. 7 shows draw force curves for an embodiment of a second cam moduleat several different draw length orientations.

FIG. 8 shows draw force curves for an embodiment of a third cam moduleat several different draw length orientations.

FIG. 9 shows draw force curves for an embodiment of a fourth cam moduleat several different draw length orientations.

FIG. 10 shows draw force curves for embodiments of four different cammodules, each module set at a first draw length orientation.

FIG. 11 shows draw force curves for embodiments of four different cammodules, each module set at a second draw length orientation.

FIG. 12 shows draw force curves for embodiments of four different cammodules, each module set at a third draw length orientation.

FIG. 13 shows draw force curves for embodiments of four different cammodules, each module set at a fourth draw length orientation.

FIG. 14 shows examples of two cam modules attached to a rotatablemember, the cam modules oriented in a first draw length orientation.

FIG. 15 shows the cam modules of FIG. 14 in a second draw lengthorientation.

FIGS. 16A-16D show embodiments of cam modules.

FIG. 17 shows a graph that compares a moment arm of the force applied bythe power cable with peak draw weight.

FIG. 18 compares embodiments of cam modules.

FIG. 19 shows a graph that compares bow axle displacement with peak drawweight.

FIGS. 20-24 each show embodiments of cam modules on a rotatable memberat a given draw length orientation.

FIG. 25 shows a graph that compares a moment arm of the force applied bythe power cable with draw length setting/orientation.

FIG. 26 shows a graph that compares a cam ratio with draw lengthsetting/orientation.

FIG. 27 shows an embodiment of a crossbow.

FIG. 28 shows a detailed, exploded view of a rotatable member of thecrossbow of FIG. 27.

FIG. 29 shows a detailed, exploded view of a rotatable member of thecrossbow of FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific embodiments of the invention. Thisdescription is an exemplification of the principles of the invention andis not intended to limit the invention to the particular embodimentsillustrated.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated.

The archery bow concept described herein presents a new dimension in camdesign that incorporates the use of a limited number of adjustable cammodules to provide a wide variety of compound bow offerings.

FIG. 1 shows an embodiment of a bow 10 that comprises a riser 12 thatsupports a first limb 14 and a second limb 16. Each limb 14, 16 isattached to the riser 12 with a fastener 15 (e.g., limb bolt), and mayalso be held by a limb cup 17. The first limb 14 supports a firstrotatable member 20 and the second limb 16 supports a second rotatablemember 22. In some embodiments, each limb 14, 16 supports an axle 24,which in turn supports the rotatable member 20, 22. In some embodiments,a central axis of the axle 24 comprises a rotation axis for the givenrotatable member 20, 22.

The bow 10 illustrated in FIG. 1 is a dual cam bow, wherein eachrotatable member 20, 22 comprises a cam 30. As shown, each cam 30comprises a cam module that can be detached from the rotatable member20, 22. In some embodiments, the two rotatable members 20, 22 aregeometrically similar to one another.

A bowstring 18 extends between the rotatable members 20, 22. The bow 10comprises two power cables 26 a, 26 b, wherein each power cable 26extends from one limb 14, 16 to the cam 30 of the opposite rotatablemember 20, 22. Each power cable 26 can be considered to have an anchorend 27, wherein the power cable 26 is anchored to the limb 14, 16, and acam end 28, wherein the power cable 26 interacts with the cam 30. Insome embodiments, the anchor end 27 of the power cable 26 terminates onthe axle 24, for example comprising a split yoke straddling the axle 24.

FIG. 2 shows an embodiment of a rotatable member 20 in greater detail.The rotatable member 20 comprises a bowstring feed out track 42extending about at least a portion of its periphery. A portion of thebowstring 18 is generally oriented in the bowstring feed out track 42when the bow is in the brace condition, and bowstring 18 is fed out fromthe bowstring feed out track 42 as the bow 10 is drawn. The cam 30comprises a power cable take up track 44 extending about at least aportion of its periphery. As the bow 10 is drawn, a portion of a powercable 26 is taken up by the power cable take up track 44.

In some embodiments, the rotatable member 20 comprises a capstan 21 anda terminal post 23. The power cable 26 b wraps around the capstan 21 ina direction (e.g. clockwise) that is opposite from the direction ofrotation of the rotatable member 20 during draw (e.g. counter-clockwise)as the power cable 26 b is traversed along its cam end 28 around thecapstan 21 toward the terminal post 23. This reverse wrapping concept isfurther described in U.S. patent application Ser. No. 12/895,610, titled“Archery Bow Cam”, filed Sep. 30, 2010, with inventor Mathew A.McPherson, the entire disclosure of which is hereby incorporated hereinin its entirety.

An orientation of the cam 30 is adjustable with respect to the rotatablemember 20, thereby changing the draw length of the bow 10. Desirably,the cam 30 can be attached to the rotatable member 20 in one of severalrotational positions. In some embodiments, the rotatable member 20comprises a plurality of apertures 32, and a fastener 34, for example inthe form of a cap screw or machine screw, is used to secure a fasteninglocation 31 of the cam 30 in alignment with a given aperture 32.Rotating the cam 30 with respect to the rotatable member 20 in thedirection that the rotatable member 20 rotates during draw will shortenthe draw length. Rotating the cam 30 with respect to the rotatablemember 20 opposite the direction that the rotatable member 20 rotatesduring draw will increase the draw length. Thus, the rotatable member 20can comprise an aperture 32 a that represents the shortest draw length,and an aperture 32 z that represents the longest draw length.

Desirably, a peak draw weight of the bow will remain substantiallyconstant throughout the various draw length orientations of the cam 30with respect to the rotatable member 20. This is true while all otheraspects of the bow 10 remain the same. For example, the limbs 14, 16 arenot changed, the limb fasteners 15 are not adjusted, etc.

The bow 10 disclosed herein allows for a greater amount of draw lengthadjustment at substantially the same draw weight than has been achievedin prior bows. For example, the various cam 30 orientations provided forin FIG. 2, specifically the apertures 32 ranging from 32 a to 32 z, willallow a draw length adjustability of approximately nine inches. FIG. 2shows a first plurality 50 of apertures 32 aligned on an arc of constantradius from the center of rotation 25, wherein apertures 32 a and 32 zare positioned on opposite ends of the first plurality 50 of apertures32. As shown, the first plurality 50 of apertures 32 includes a total ofnine apertures 32, wherein the first aperture 32 a provides for ashortest draw length, such as 22 inches, and the last aperture 32 zprovides for a longest draw length, such as 30 inches. Each intermediateaperture 32 provides for a 1 inch incremental change in the draw length.

In some embodiments, the rotatable member 20 further comprises a secondplurality 52 of apertures 32 aligned on a second arc. Desirably, allapertures 32 in the second plurality 52 are aligned on an arc ofconstant radius from the center of rotation 25. Desirably, the apertures32 in the second plurality 52 are rotationally staggered with respect tothe apertures 32 in the first plurality 50. The cam 30 further comprisesa second fastening location 33, wherein the second fastening location 33can be aligned with apertures 32 in the second plurality 52. Thefastener 34 can be removed from the first fastening location 31 and usedin the second fastening location 33 with apertures 32 of the secondplurality to achieve a greater degree of draw length adjustability. Insome embodiments, the fastener 34 is threaded into the fasteninglocation 33. As shown in FIG. 2, the second plurality 52 of apertures 32includes a total of eight apertures 32, wherein each aperture 32provides for a 1 inch incremental change in the draw length. The secondplurality 52 of apertures 32 is staggered to provide for draw lengthadjustments that fall between the draw lengths achieved with the firstplurality 50 of apertures 32. Thus, the two pluralities 50, 52 ofapertures 32 allow for adjustment of the draw length from 22 inches to30 inches in half-inch increments.

In at least some embodiments, the large draw length adjustabilityprovided by the bow 10 disclosed herein, while maintaining substantiallythe same peak draw weight, stems from a cam 30 design wherein the bow 10reaches peak draw weight as the power cable 26 is taken up at apredetermined peak weight location 46 of the power cable take up track44, regardless of the particular draw length setting. Desirably, thedraw force progressively increases from brace orientation until the draworientation where peak weight is reached (i.e. when the power cable 26is taken up at the peak weight location 46), after which the draw forcewill decrease. This is different from prior art rotatable draw lengthmodules, which generally resulted in inherent significant adjustment ofpeak weight as an undesirable side effect of adjusting draw length.

From FIG. 2, it can be seen that if the cam 30 were adjusted to theshortest draw length (e.g. aperture 32 a being used), the power cable 26is taken up into the peak weight location 46 quickly upon draw. If thecam 30 were adjusted to the longest draw length (e.g. aperture 32 z),the rotatable member 20 must rotate a greater amount before the powercable 26 is taken up into the peak weight location 46.

In some embodiments, the power cable 26 does not contact the cam 30 whenthe bow 10 is in the brace condition. In some embodiments, the powercable 26 does not contact the cam 30 when the bow 10 is in the bracecondition, for any rotational orientation of the cam 30. In someembodiments, the power cable 26 does not contact the cam 30 when the bow10 is in the brace condition for some of the rotational orientations ofthe cam 30, but does in other(s).

Although FIGS. 1 and 2 show an embodiment where the cam 30 comprises afastening location 31 and the rotatable member 20 comprises a pluralityof apertures 32, any suitable mechanism can be used to attach the cam 30to the rotatable member 20 in a plurality of orientations. For example,in some embodiments (not illustrated), a rotatable member 20 cancomprise a fastening location, and the cam 30 can comprise a pluralityof apertures.

In some embodiments, a bow 10 can be provided with multiple cam 30modules, wherein each module provides for a different peak draw weight.In some embodiments, each cam module 30 can be arranged in a pluralityof orientations with respect to the rotatable member 20 to adjust drawlength as described above.

FIGS. 3A-3D show several embodiments of cam 30 modules that can be usedwith the bow of FIG. 1. A first cam module 30 a, as shown in FIG. 3A,will produce a first peak draw weight, such as 40 pounds. Shown in FIG.3B, a second cam module 30 b will produce a second peak draw weight,such as 50 pounds. Shown in FIG. 3C, a third cam module 30 c willproduce a third peak draw weight, such as 60 pounds. Finally, shown inFIG. 3D, a fourth cam module 30 d will produce a fourth peak drawweight, such as 70 pounds. Desirably, each cam module 30 provides for aparticular peak draw weight when used in the bow 10, while all otheraspects of the bow 10 remain the same. For example, the limbs 14, 16 arenot changed, the limb fasteners 15 are not adjusted, etc.

It should be noted that prior art bows are generally constructed havingthe limbs and riser as separate pieces, which allows the limbs to bechanged, for example to adjust draw weight. When using the rotatablemember 20 and cam 30 disclosed herein, in some embodiments, the riser 12and limbs 14, 16 can comprise a single, unitary assembly of components.Further, in embodiments of the bow 10 disclosed herein that utilizeseparate limbs 14, 16 and limb fasteners 15, the fasteners 15 can alsobe adjusted to adjust (e.g. fine tune) the draw force of the bow 10.

Desirably, a peak draw weight of the bow 10 will remain substantiallyconstant throughout the various draw length orientations of the cam 30with respect to the rotatable member 20.

The terms “substantially constant” or “substantially similar” as usedherein when referring to peak draw weights means that there is less than5% variation in the peak draw weight, as described below. It should benoted that a greater range of draw length adjustability generallyresults in a greater variation in the actual peak draw weight of thebow.

“Let-off” as used herein refers to a reduction in the draw force of thebow that occurs after peak draw force as the bow is drawn. Let-off isgenerally accomplished via the bow's compounding action.

The “draw lengths” referred to herein are generally directed to “full”draw lengths of the bow.

In some embodiments, the peak draw weight of the bow does not changemore than 5 pounds over at least 60% of the entire draw lengthadjustment range. In some embodiments, the peak draw weight of the bowdoes not change more than 4 pounds over at least 60% of the entire drawlength adjustment range. In some embodiments, the peak draw weight ofthe bow does not change more than 5 pounds over at least 75% of theentire draw length adjustment range.

Each successively larger cam module 30 is sized relative to theprevious, lower draw weight, cam module 30 to provide for a greateramount of power cable 26 take up during a given span of draw length,when compared to a smaller module. Thus, the power cable take up track44 is longer in the larger cam modules 30. A greater amount of powercable 26 take up results in a greater amount of limb 14, 16 flex, andmore force is required to draw the bow.

As further shown in FIGS. 3A-3D, each cam module 30 comprises a let-offportion 36 and a high weight portion 38. As the bow 10 is drawn frombrace condition, the power cable 26 is first taken up in the high weightportion 38 of the cam module 30. As the bow 10 reaches full draw, thepower cable 26 is taken up in the let-off portion 36 of the cam module30. In order to achieve the desired draw force reduction/let-off at fulldraw, the power cable 26 must move closer to the center of rotation 25of the rotatable member 20/cam module 30 at full draw (thus reducing thelength of the moment arm of the force applied to the rotatable member 20by the power cable 26, reducing the torque applied to the rotatablemember 20 by the power cable 26 and also reducing the bowstring 18 drawforce necessary to counteract that torque to retain full draw).Therefore, the power cable take up track 44 at the let-off portion 36 isoriented close to the center of rotation 25 in all cam modules 30 a-30d. In some embodiments, a distance between the center of rotation 25 andthe let-off portion 36 is the same for all cam modules 30 a-30 d.

In some embodiments, the let-off portion 36 can be considered to be theportion of the power cable take up track 44 that is closest to thecenter of rotation 25. In some embodiments, a maximum let-off portion isthe portion of the power cable take up track 44 that is closest to thecenter of rotation 25.

A distance d between the power cable take up track 44 at the high weightportion 38 and the center of rotation 25 decreases with eachsuccessively smaller cam module 30. In some embodiments, the distance dof the third cam module 30 c is approximately 84% of the distance d ofthe fourth cam module 30 d. In some embodiments, the distance d of thesecond cam module 30 b is approximately 80% of the distance d of thethird cam module 30 c. In some embodiments, the distanced of the firstcam module 30 a is approximately 76% of the distanced of the second cammodule 30 b.

In embodiments of the bow 10, wherein a given cam module 30 is rotatablewith respect to the rotatable member 20 to adjust draw length, thedistance d between the center of rotation 25 and the take up track 44 atthe high weight portion 38 will be substantially constant across apredetermined arc length 40 (see e.g. cam module 30 a in FIG. 3A). Thearc length 40 required will depend on the range of adjustability of thecam module 30 with respect to the rotatable member 20. For example, oneend of the arc length 40 represents a contact location for the powercable 26 as the bow 10 reaches peak draw weight in the shortest drawconfiguration, and the other end of the arc length represents a contactlocation for the power cable 26 as the bow reaches peak draw weight inthe longest draw configuration. For embodiments of lower weight cammodules 30 and bows 10 that provide a lesser amount of draw lengthadjustability, the distance d is more likely to be constant across thearc length 40. For embodiments of bows 10 that provide for a greateramount of draw length adjustability, it is more likely that the distanced may be adjusted slightly across the predetermined arc length 40 (e.g.at one end of the arc length 40), especially in the largest cam module30 d, to achieve the desired draw force results.

FIGS. 4A-4D show alternative embodiments of cam modules 30 as-30 ds thatfurther comprise a rotation stop 60 extension of the power cable take uptrack 44. The shape of the high weight portion 38 of each cam module 30as-30 ds in FIGS. 4A-4D is similar to that of the corresponding cammodule 30 a-30 d in FIGS. 3A-3D. Each rotation stop 60 comprises anextra portion of power cable take up track 44 that extends beyond thelet-off portion 36 of the cam module 30 and is oriented to stop rotationwhen the power cable 26 enters the power cable take up track 44 in therotation stop 60, for example as illustrated via the dashed line in FIG.4D. In some embodiments, a rotation stop 60 comprises a straightextension of the power cable take up track 44 beyond the let-off portion36.

FIGS. 5A and 5B show an embodiment of a bow 10 at a full draworientation. The second rotatable member 22 comprises a third cam module30 c, for example as shown in FIG. 3C. The first rotatable member 20comprises a third cam module 30 cs that comprises a rotation stop 60,for example as shown in FIG. 4C. A power cable 26 is in contact with therotation stop 60 such that further rotation/draw is prevented. The cammodule 30 c of the second rotatable member 22 does not have a portionthat stops rotation—thus, only one mechanism to stop rotation isincluded on the bow 10. A bow 10 having a single rotation stop 60mechanism is generally more comfortable to draw than a bow having dualrotation stops, as the dual stops tend to accentuate a slight differencein cam synchronization. A bow 10 having a rotation stop 60 as a portionof the cam 30 is more comfortable to draw than other types of rotationstop mechanisms (such as an extension of the rotatable member that hitsa limb 14, 16 to abruptly stop rotation) because the stop 60 isrelatively soft due to give in the power cable 26.

Thus, in some embodiments, a bow 10 comprises a first cam 30 c and asecond cam 30 cs, wherein the power cable take up tracks 44 of the cams30 c, 30 cs are largely similar to one another through substantially allof the draw length (thus being a dual or twin cam bow), but the secondcam 30 cs comprises a rotation stop 60 and the first cam 30 c does not.

In some embodiments, a bow 10 can include cam modules 30 on bothrotatable members 20, 22 that are identical. Thus, in some embodiments,both cam modules 30 can include a rotation stop 60, and in someembodiments, neither cam module 30 includes a rotation stop 60.

It should also be noted that cam modules 30 can be used that are similarwith respect to their functional areas, but can be dissimilar withrespect to any non-functional areas.

Turning to FIG. 18, this figure shows a comparison of embodiments offour cam modules 30 a-30 d, wherein each module 30 is suitable toproduce substantially the same peak draw weight at a plurality of drawlength orientations. A peak weight location 46 is shown for each cammodule 30. Specifically, the peak weight location 46 indicated is thelocation that the given cam module 30 reaches peak draw weight whenoriented on the rotatable member 20 in the maximum draw lengthorientation. It can be seen that the distance from a center of rotation25 to the peak weight location 46 progressively increases as the modulesincrease in peak weight. Further, the distance at issue continues for apredetermined distance portion of the cam 30, resulting in a cable takeup track 44 that comprises an arc y having a substantially constantradius from the center of rotation 25. In FIG. 18, the arc y isindicated for the largest cam module 30 d.

In some embodiments, a cam module 30 comprises a groove 35 thatcomprises a first engagement location with the rotatable member body 20.A second engagement location comprises the fastening location 31 (FIG.3A). In some embodiments, the groove 35 is asymmetrical. In someembodiments, the groove 35 comprises a hook arranged to engage the bodyof the rotatable member 20. In some embodiments, the groove 35 comprisesan arcuate surface 37 arranged to engage the body of the rotatablemember 20. In some embodiments, the arcuate surface 37 of the cam module30, and a corresponding arcuate surface of the body of the rotatablemember 20, are semicircular. In some embodiments, the arcuate surface 37comprises a peak that is located opposite said fastening location 31(FIG. 3A). Thus, in some embodiments, a cam module 30 is engaged to arotatable member 20 body using only the arcuate surface 37 and a singlefastening location 31/fastener 34. This can allow the cam module 30 tobe changed quickly and easily, without disassembly of other portions ofthe bow 10.

FIG. 6 shows a plurality of draw force curves as related to draw lengthfor an embodiment of a bow 10 using a first size cam module 30 a. FIG. 6indicates true draw length, whereas archery bows are often sold with anArchery Trade Association (ATA) draw length specification. ATA drawlength is generally 1.75″ longer than true draw length. Therefore, atrue draw length of 28.25″ on FIG. 6 would be sold as a bow having a 30″ATA draw length.

In FIG. 6, the desired peak draw weight for the given cam module 30 a isapproximately 40 pounds. A draw force curve is provided for each of ninerotational orientations of the cam module 30 with respect to therotatable member 20 (e.g. a curve is provided for each of the nineapertures 32 a-32 z included in the first plurality 50 of apertures 32as shown in FIG. 2). As previously noted, a greater amount of drawlength adjustability generally leads to greater variation in peak drawweight. For example, the six longest curves, which correspond to drawlength adjustment ranging from 30″ to 25″, have a peak weight variationranging from greater than 41 pounds to approximately 42.5 pounds—avariation of only 1.5 pounds.

It can also be noted that, in some embodiments, the shortest draw lengthorientations tend to result in a lower draw force. In some embodiments,adjustment of draw length near the longer draw length orientationsresults in very little actual draw weight change, whereas adjustment ofdraw length near the shorter draw length orientations results in alarger amount of actual draw weight change. In some embodiments, this isdesirable because archers requiring a shorter draw length (e.g.children) may also prefer a slightly lower peak draw force.

As further illustrated in FIG. 6, at each length adjustment setting, thebow has a significant let-off. In some embodiments, the let-off is atleast 25%; in some embodiments, the let-off is at least 40% and, in someembodiments, at least 45%, 50%, 55%. In some embodiments, the let-off isat least 60% and, in some embodiments, at least 65%.

FIG. 7 shows a plurality of draw force curves similar to FIG. 6, but foran embodiment of a bow 10 using a second size cam module 30 b. In FIG.7, the desired peak draw weight for the given cam module 30 b isapproximately 50 pounds.

As further illustrated in FIG. 7, at each length adjustment setting, thebow has a significant let-off. In some embodiments, the let-off is atleast 25%; in some embodiments, the let-off is at least 40% and, in someembodiments, at least 45%, 50%, 55%. In some embodiments, the let-off isat least 60% and, in some embodiments, at least 65%.

FIG. 8 shows a plurality of draw force curves similar to FIG. 7, but foran embodiment of a bow 10 using a third size cam module 30 c. In FIG. 8,the desired peak draw weight for the given cam module 30 c isapproximately 60 pounds.

As further illustrated in FIG. 8, at each length adjustment setting, thebow has a significant let-off. In some embodiments, the let-off is atleast 25%; in some embodiments, the let-off is at least 40% and, in someembodiments, at least 45%, 50%, 55%. In some embodiments, the let-off isat least 60% and, in some embodiments, at least 65%.

FIG. 9 shows a plurality of draw force curves similar to FIG. 8, but foran embodiment of a bow 10 using a fourth size cam module 30 d. In FIG.9, the desired peak draw weight for the given cam module 30 d isapproximately 70 pounds. As previously noted, a greater amount of drawlength adjustability generally leads to greater variation in peak drawweight. For example, the six longest curves, which correspond to drawlength adjustment ranging from 30″ to 25″, have a peak weight variationranging from approximately 72 pounds to approximately 74 pounds—avariation of only 2 pounds.

As further illustrated in FIG. 9, at each length adjustment setting, thebow has a significant let-off. In some embodiments, the let-off is atleast 25%; in some embodiments, the let-off is at least 40% and, in someembodiments, at least 45%, 50%, 55%. In some embodiments, the let-off isat least 60% and, in some embodiments, at least 65%.

In some embodiments, for all modules at all length settings, the let-offis at least 40%, 45%, 50%, 55%, 60% and, in some embodiments, at least65%.

FIG. 10 shows a plurality of draw force curves as related to draw lengthfor multiple cam modules 30 a-30 d, each at a similar draw lengthsetting, specifically a setting corresponding to a draw length ofapproximately 24 inches. FIG. 11 shows a plurality of draw force curvesfor multiple cam modules 30 a-30 d, each at a similar draw lengthsetting, specifically a setting corresponding to a draw length ofapproximately 26 inches.

FIG. 12 shows a plurality of draw force curves for multiple cam modules30 a-30 d, each at a similar draw length setting, specifically a settingcorresponding to a draw length of approximately 28 inches.

FIG. 13 shows a plurality of draw force curves for multiple cam modules30 a-30 d, each at a similar draw length setting, specifically a settingcorresponding to a draw length of approximately 30 inches.

The archery bow 10 system described herein combines the desirableattributes of rotatable cam modules 30 and interchangeable cam modules30 in such a manner that a single bow 10 provided with a limited numberof module sizes is able to fill the needs of the majority of theconsumer market. Previously, a single bow could not be adjusted to besuitable for all the draw lengths and draw weights described hereinmerely by changing a cam module. For example, draw weights havetraditionally been adjusted by providing a bow with different limbs.Often a unique cam design was required for each available strength ofbow limb. Thus, in order to provide bows for a range of consumers, a bowsupplier was required to stock several versions of cams and severalversions of limbs for a given bow model. The bow 10 described hereinprovides for the same range of adjustability while requiring only onelimb type, one rotatable member type, and a few cam modules 30. Thisconcept can lower manufacturing costs, drastically reduce the inventoryrequired of retailers and provide the consumer with a product that canbe adjusted to meet changing needs.

Design Example

An example of a design procedure for developing the various cam modules30 is discussed below.

It should be noted that early compound bows were shaped quitedifferently from current compound bows. Early compound bows were muchlonger (e.g. longer axle-to-axle length) and had smaller rotatablemembers. A portion of their draw length was provided by limb flex and acorresponding reduction in axle-to-axle length. Conversely, current bowsachieve a greater amount of draw length by feeding greater amounts ofbowstring out from larger rotatable members. This evolution in bowdesign allows the cam module concept disclosed herein to be easier toachieve, whereas such a system may not have been possible in oldercompound bow designs.

Referring again to FIGS. 1 and 2, in general, the bowstring feed outtrack 42 of a rotatable member 20 should be a size and length thatenables a sufficient amount of bowstring to feed out, to achieve thedesired maximum draw length for the bow 10. The power cable take uptrack 44 of a cam 30 is sized and shaped to take up an appropriateamount of power cable 26, causing an appropriate amount of limb 14, 16flex to achieve the desired draw weight for that cam 30. Further, a camratio exists between the rotatable member 20 and the cam module 30, asdiscussed in greater detail below. The cam ratio controls the forces inthe power cable 26 and bowstring 18 (specifically between points thatare tangent to the power cable and tangent to the bowstring relative tothe center of rotation 25) at any position of the draw cycle. This camratio determines the draw force profile and the effort that is requiredto draw the bow.

A basic concept of a compound bow is that at some point during draw, theamount of force that must be applied to the bowstring 18 to draw the bowincreases to a maximum and subsequently decreases. Generally, the forcerequired to draw the bowstring 18 beyond the position at which maximumdraw force is achieved is either constant or is decreasing as thebowstring 18 is drawn to the full draw length. This concept can be seenin FIGS. 6-13 as the draw force curves reach a maximum and then let off.

Each specific set (e.g. pair) of cam modules 30 provides a given maximumdraw weight. Simultaneously, each set of cam modules 30 can be adjustedto achieve a plurality of predetermined draw lengths. Due to the rangeof draw lengths, it is desirable that peak draw weight be achieved earlyin the draw cycle, allowing the desired peak weight to be achieved evenfor the shortest possible draw length.

For the main example bow described herein, the shortest desired drawlength is approximately 24 inches, based on the Archery TradeAssociation (ATA) guidelines. A 24″ (ATA) draw length translates to atrue draw length of approximately 22.25″. Using this draw length in abow having a brace height of approximately 7″, the power stroke of thebow would be approximately 15.25″ (22.25″-7″). It is often pleasurableif a bow reaches peak draw weight at or before half way through thepower stroke. Thus, a good starting design goal would be to reach peakweight around 7-8″ into the power stroke. This translates to a desire toreach peak weight at approximately 15″ (ATA) draw length. Thus, there isa design goal to reach peak draw weight at approximately 15″ (ATA) drawlength for each specific cam module 30 set. In the main example bow 10described herein, the modules are designed to achieve approximately 40#,50#, 60# and 70# peak draw weights.

By way of example, using a rotatable member 20 as shown in FIG. 1 andone of the above cam modules 30 attached to the rotatable member 20 inthe longest draw length orientation, the rotatable member 20 rotatesapproximately 50 degrees from brace position to its position when thebowstring reaches 15″ (ATA) draw length. Desirably, at this point thebowstring 18 reaches the aforementioned extreme and the bow 10 hasachieved maximum draw weight. This in turn establishes a datum pointbaseline from which to design successively sized cam modules 30.

Because the same rotatable member 20 and bowstring feed out track 42 areused regardless of the specific cam module 30 a, b, c, d, therelationship of bowstring draw length to rotational position of therotatable member 20 is very nearly the same for any given draw lengthselection. Thus, at the desired 15″ True draw length, the moment arm ofthe rotatable member 20 is constant, and tension in the bowstring (i.e.draw force) is directly related to the moment arm of the module 30.Specifically, the moment arm associated with the power cable 26 isdefined as the distance between the power cable 26 and a line extendingfrom the center of rotation 25 parallel to the power cable 26, forexample as shown in FIG. 14 and labeled ACm for module 30 a and DCm formodule 30 d. Stated differently, the moment arm associated with thepower cable 26 is the distance, measured perpendicular to the point oftangency, between the power cable 26 and a line extending from thecenter of rotation 25. This point of tangency can define one end of thearc length 40 described with respect to the first module 30 a of FIG.3A. If the cam module 30 radius (e.g. distance din FIGS. 3A-3D) isincreased at this point of tangency, the load in the bowstring 18 mustincrease proportionately to keep the system in balance. This increaseforms the basis for designing cam modules 30 that result in the desiredpeak draw weight for a given cam module 30.

In starting to build a set of cam modules 30, it is suggested to startwith either the lowest draw weight or the highest draw weight desired,and position the selected cam module 30 in the maximum draw lengthconfiguration.

FIG. 14 shows a rotatable member 20 in a partially drawn orientation,wherein the bow 10 is drawn to the 15″ True draw length positiondescribed above, wherein peak draw weight is desired. FIG. 14 shows afirst cam module 30 a and a fourth cam module 30 d, each oriented in amaximum draw length configuration. In the brace condition, the powercable 26 is tangent to point T₁ when the first cam module 30 a is used.In the rotational position of FIG. 14, the power cable 26 is tangent topoint P₁. Thus, from brace condition to the orientation of FIG. 14, therotatable member 20 has rotated an amount shown by angle Φ.

With the rotatable member 20 in this position of FIG. 14, the forcerequired to hold the bowstring has reached maximum draw weight. Tensionin the bowstring 18 acts on the rotatable member 20 through moment armBm, which is perpendicular to bowstring 18. This force is counteractedby the force applied by the power cable 26 at point P₁, which is atorque amounting to the tension in the power cable 26 multiplied by themoment arm ACm.

Point P₁ is significant because during draw from brace condition untilthe rotational orientation of FIG. 14, wherein the power cable 26reaches point P₁, the force necessary to draw the bowstring 18 isprogressively increasing. Once the contact point between the power cable26 and the cam module 30 passes point P₁, the draw force is eitherconstant or is decreasing until the desired draw length is reached. Theprofile of the cam module 30 a on either side of P₁ is dictated by theseincreasing and then decreasing draw force requirements.

FIG. 14 shows similar tangent points for an example of a largest cammodule 30 d. T₂ represents the power cable 26 tangent point at bracecondition, and P₂ represents the power cable 26 tangent point at therotational orientation of FIG. 14. Just as the moment arm ACm from thecenter of rotation 25 to the point P₁ on the first cam module 30 adetermines the peak draw weight for the first cam module 30 a, the sameis true for the fourth cam module 30 d. The force applied to therotatable member 20 by the power cable 26 at point P₂ is a torqueamounting to the tension in the power cable 26 multiplied by the momentarm DCm. This force must be counteracted by the bowstring 18, forexample by increasing tension/draw force in the bowstring becausebowstring moment arm Bm is unchanged when modules 30 are swapped. Theresult is that the peak draw weight has been increased to the desiredamount by the larger cam module 30 d.

Additional cam module 30 moment arms can be considered to result inadditional cam modules 30 that will result in any desirable peak drawforce.

While the above explanation helps to determine the location of certainportions of the cam modules 30 (e.g. P₁, P₂) to achieve desired peakdraw force, another design goal of at least some embodiments of a bow 10is that each cam module 30 can be adjusted with respect to the rotatablemember 20 to achieve a large number of draw lengths. In someembodiments, each cam module 30 is adjustable to achieve a draw lengthadjustment range of at least seven inches, while still maintaining asubstantially constant peak draw weight.

FIG. 15 shows the rotatable member 20 in the same rotational orientationof FIG. 14, specifically the 15″ True draw orientation that achieves themaximum draw weight. The cam modules 30 a, 30 d have been repositionedto achieve a draw length that is 7″ shorter than that of FIG. 14. Forexample, the cam modules 30 a, 30 d are affixed to aperture 32 x, whichis the 7^(th) aperture in the first plurality 50 of apertures 32. FIG.15 shows that each cam module 30 is designed such that the power cablemoment arms ACm, DCm are of sufficient length, in this orientation, sothe power cable 26 creates the same (or substantially similar) force asin FIG. 14, resulting in the bow reaching the maximum draw weight atthis point in the draw cycle. For example, the first cam module 30 amaintains a substantially constant moment arm ACm from point P₁ (peakdraw weight in FIG. 14) to point R₁ (peak weight in FIG. 15). In thiscase, the moment arm ACm of the first cam module 30 a remainssubstantially constant over an angular range of a, causing the maximumdraw weight of the bow 10 to be substantially constant over the entirerange of draw lengths between the draw length of FIG. 14 and the drawlength of FIG. 15.

The situation is slightly different in the case of the fourth cam module30 d (e.g. the largest draw weight module). As the cam modules 30 getlarger and the forces in the bow increase, the moment arm DCm of therelatively large cam modules 30 may require some adjustment at an end ofthe rotational adjustment range. Because the high weight portion 38 ofthe fourth cam module 30 d is scaled up as compared to other modules, ittakes up more power cable 26 during rotation. This causes greater limbflex and increased tension in the power cable 26. This increase in powercable 26 tension requires that the power cable moment arm DCm be reducedslightly to maintain peak draw weight at levels similar to otherorientations of the fourth cam module 30 d. The result is that theprofile of the larger cam modules 30 are more likely to have a compoundcurvature over the angular span 6, which spans from P₂ to the tangentpoint R₂ of the power cable 26 in FIG. 15.

FIGS. 16A-16D show example design specifics for embodiments of cammodules 30 a-30 d, when oriented in the longest draw length setting withrespect to the rotatable member 20. In such an orientation, the angularrotation Φ of each cam module 30, as the bow is drawn from bracecondition, represented via T_(c), to the point of maximum draw weightP_(w) is approximately 50 degrees, and the total cam rotation from braceto full draw is approximately 215 degrees.

In particular, the point of tangency P_(w) between the power cable 26and the cam module 30 when maximum draw weight is attained during thedraw cycle, is shown. Also shown is the radius R40, R50, R60, R70 fromthe center of rotation 25 to that tangent point P_(w) at maximum drawweight for each module. This radius R40, R50, R60, R70 increases as cammodule 30 increases with bow weight. Further, the amount of power cable26 that is taken up by the periphery of the module as the bow is drawnis represented by U. In particular, in some embodiments, for the maximumdraw length configuration, U_(d) is approximately 3.5″ for the 70#module U_(c) is approximately 3.0″ for the 60# module; U_(b) isapproximately 2.6″ for the 50# module; and U_(a) is approximately 2.2″for the 40# module.

FIG. 17 shows a graph plotting the radius R40, R50, R60, R70, in inches,from FIG. 16 against the peak draw weight of the given module 30. When alinear fit line is added to the plot, the relationship between the fitline and the plotted line yields a correlation coefficient of 0.9997.Therefore, the scaling from one draw weight module to another is astraight forward process relative to their radius at the point oftangency when maximum draw weight is attained in the draw cycle. Inother words, if a bow having a max draw weight of 45# is desired, forexample, the radius can be determined according to the linear fit line,as depicted.

Another method to approximate scaling up or down of cam module 30 sizesis to compare the amount of power cable 26 take up that would berequired on the next module 30 based on the amount of power cable 26take up in the present module. FIG. 19 shows a near linear relationshipbetween power cable 26 take up and peak draw weight. In FIG. 19, thespecific values for power cable 26 take up are approximated as half ofthe axle-to-axle displacement, in inches, upon draw (e.g. the powercable take up results in axle-to-axle displacement).

FIGS. 20-24 show an embodiment of a rotatable member 20 with cam modules30 a-30 d arranged at different draw lengths. In each instance, the bowis at its peak draw weight. The bowstring moment arm is indicated by Bmand power cable moment arms are indicated specifically in FIG. 20 byACm, BCm, CCm, and DCm and, more generally in FIGS. 21-24 by PCm.Further, the tangent points are illustrated via Pwa, Pwb, Pwc, and Pwdfor the respective cam modules 30 a, 30 b, 30 c, and 30 d.

FIG. 20 shows the 22″ ATA draw length at peak weight.

FIG. 21 shows the 24″ ATA draw length at peak weight.

FIG. 22 shows the 26″ ATA draw length at peak weight.

FIG. 23 shows the 28″ ATA draw length at peak weight.

FIG. 24 shows the 30″ ATA draw length at peak weight. Values from theseFigures are shown in charts 1 and 2, below.

Chart 1:

Power Cable Moment Arm (PCm) at Peak Draw Weight (in inches) 40# 50# 60#70# 30″ 0.656 0.828 1.011 1.187 28″ 0.659 0.831 1.016 1.191 26″ 0.660.823 0.995 1.137 24″ 0.624 0.765 0.897 0.994 22″ 0.569 0.657 0.7510.805

Chart 2:

Bowstring Moment Arm (Bm) at Peak Draw Weight (in inches) 30″ 1.314 28″1.320 26″ 1.320 24″ 1.315 22″ 1.319

FIG. 25 shows a graph created using data from chart 1, mapping the drawlength against the power cable moment arm PCm. FIG. 25 shows therelationship of the power cable moment arms across the multiple module30 sizes. When one module size is known, this relationship can be usedto calculate the basis for other module sizes.

A cam ratio between the bowstring moment arm Bm and the power cablemoment arm PCm is shown in the chart below for each module 30 a-30 d atvarious draw length orientations. The cam ratio is calculated bydividing the bowstring moment arm, Bm, by the power cable moment arm,PCm.

Chart 3:

Cam Ratio Calculation at constant bowstring moment arm Bm 40 50 60 70 302.008 1.591 1.303 1.110 28 1.998 1.585 1.296 1.106 26 1.995 1.600 1.3241.158 24 2.111 1.722 1.468 1.325 22 2.315 2.005 1.754 1.636

FIG. 26 shows a graph of the data of chart 3.

In some embodiments (e.g. the bow of the design example describedabove), each of the three smaller modules 30 a, 30 b, 30 c do notcontact the power cable 26 when the bow 10 is in the brace condition,regardless of the draw length orientation of the module. The largestmodule 30 d tends to have some contact with the power cable 26 due toits larger size/radius, wherein a portion of the power cable 26 isoriented in a portion of a groove that extends around the periphery ofthe module 30 d (e.g. the power cable track). The contact is veryslight, wherein the power cable 26 is not displaced from its orientationat brace due to the module—e.g. the power cable 26 is not loaded in alateral direction by the module 30 d when the bow is in the bracecondition.

In some embodiments, the peak draw weight of the bow changes less than5% of the desired peak draw weight over at least 75% of the entire drawlength adjustment range. Stated differently, for the 40# module with anadjustment range from 22″-30″ ATA draw length settings shown in FIG. 6,for example, the peak draw weight changes by 2 pounds or less (5% of 40pounds) over at least the 24″-30″ ATA draw length settings.

In some embodiments, the peak draw weight of the bow changes less than4% of the desired peak draw weight over at least 75% of the entire drawlength adjustment range. With regard to FIG. 7, for example, for theillustrated 50# module, the peak draw weight changes by 2 pounds or less(4% of 50 pounds) over at least the 24″-30″ ATA draw length settings.

Further relationships are shown for the 60# and 70# modules in FIG. 8and FIG. 9. Additionally, it will be appreciated that, in someembodiments, the peak draw eight of the bow changes less than 3% of thedesired draw weight over at least 60% of the entire draw lengthadjustment, for example where the draw length can be adjusted between22″ and 30″ ATA. With reference to FIG. 9, for example, the peak drawweight changes by 2 pounds or less for the 25″-30″ ATA draw lengthsettings.

Further, in some embodiments, for example where the module is designedto be adjustable between a more limited range of draw length settings,the peak draw weight of the bow changes less than 3% of the desired drawweight for the entire draw length adjustment range. Stated differently,in some embodiments, the modules are adjustable, for example, onlybetween 25″ and 30″ ATA draw length settings. With reference to FIG. 9,then, the difference in maximum draw weight between the 25″ setting and30″ setting is approximately 1.5 pounds. 1.5 pounds divided by thedesired maximum draw weight of 70 pounds yields a variation ofapproximately 2.1%, which is less than 3%. Therefore, where the moduleis limited to adjustability between 25″ and 30″, the variation in peakdraw weight is confined to a narrower range.

Moreover, in some embodiments, the peak draw weight of the bow changesless than 3% of the desired draw weight (e.g., 40#, 50#, 60#, 70#) forthe entire adjustment range. For example, when fitted with 40#, 50#,60#, or 70# modules, each being adjustable between 25″ and 30″ ATAranges, the peak draw weight of the bow changes less than 3%.

Although the bulk of this disclosure is directed to dual cam bows, themodule 30 concept described herein can be applied to any suitable typeof bow, such as single cam bows, cam-and-a-half bows, CPS bows, twin cambows, dual sync or binary cam bows, etc.

The bow 10 concept described herein can be combined with a power cableforce vectoring anchor, for example as described in U.S. Pat. No.7,946,281 and U.S. Pat. No. 8,020,544, the entire disclosures of whichare hereby incorporated herein in their entireties.

The cam module 30 concept can also be applied to crossbows, allowing acrossbow owner to vary the draw weight of the crossbow at will bychanging a module. This concept can allow a crossbow to be more of aversatile sporting device than strictly a hunting device. The consumercan adjust the draw weight to a value that is no greater than necessaryfor the specific shooting need. Thus, the crossbow can be adjusted to bemore pleasurable for recreational target shooting, for example.

Turning to FIG. 27, an example of a suitable crossbow 110 is shown. Thecrossbow 110 comprises a bow portion 113 and a stock portion 115, whichare securely attached to one another. The bow portion 113 comprises afirst limb 114, a second limb 116, and at least one rotatable member120. The rotatable member 120 comprises a cam module 130, an example ofwhich is shown in greater detail in FIGS. 28 and 29.

The stock portion 115 comprises a trigger 148 and a latch 147, which isreleased by pulling the trigger 148, to fire a bolt or arrow (notshown). The bow portion 113 further comprises a prod 119. Furtherdetails of a crossbow structure can be found in U.S. Application No.61/699,244, titled, “Self-Aligning Crossbow Interface,” with inventorMathew A. McPherson, filed on Sep. 10, 2012, the contents of which areherein incorporated by reference.

With regard to FIGS. 28 and 29, a cam module 130 is shown therein. Thecam module 130 is designed for a predetermined maximum draw weight. Thecam module 130 can be swapped for a cam module which produces a greateror lesser maximum draw force, as discussed above with respect to bow 10and cam 30. In this way, the crossbow 110 can be suited as desired bythe user simply by swapping cam modules 130.

Further, it will be appreciated that the draw length of the crossbow 110remains the same when one weight cam module is replaced with another,thus eliminating the added complexity of incorporating the adjustabledraw length feature in the crossbow application.

Finally, in some embodiments, the cam module 130 is attached to therotatable member 120 with one or more fasteners 134. In someembodiments, the fastener(s) 134 comprise screws that are threaded intothe cam module 130.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this field of art. All these alternatives andvariations are intended to be included within the scope of the claimswhere the term “comprising” means “including, but not limited to.” Thosefamiliar with the art may recognize other equivalents to the specificembodiments described herein which equivalents are also intended to beencompassed by the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

1-16. (canceled)
 17. An archery bow comprising: a riser, a first limband a second limb; a first rotatable member supported by the first limb;a second rotatable member supported by the second limb; a bowstringextending between the first rotatable member and the second rotatablemember; a power cable; the first rotatable member arranged to rotatableabout a first axis, the first rotatable member comprising a body, a cammodule and a fastener attaching the body to the cam module, the bodydefining a bowstring track, the cam module defining a power cable track,the body comprising a plurality of apertures aligned on an arc ofconstant radius from the first axis, the plurality of aperturescomprising a first aperture, an intermediate aperture and a lastaperture, the cam module comprising a fastening location aperture, thecam module rotatable with respect to the body about the first axis, thecam module attachable to the body in a plurality of positions, theplurality of positions comprising a first position, an intermediateposition and a last position, in the first position, the fasteninglocation aperture aligned with the first aperture, in the intermediateposition, the fastening location aperture aligned with the intermediateaperture, in the last position, the fastening location aperture alignedwith the last aperture.
 18. The archery bow of claim 17, the pluralityof apertures comprising a plurality of intermediate apertures.
 19. Thearchery bow of claim 17, the plurality of apertures comprising sevenintermediate apertures.
 20. The archery bow of claim 17, the secondrotatable member comprising a second body, a second cam module and asecond fastener attaching the second body to the second cam module. 21.The archery bow of claim 17, wherein the cam module and the second cammodule comprise different shapes.
 22. The archery bow of claim 17,wherein an outer periphery of the cam module does not surround the firstaxis.
 23. The archery bow of claim 17, an outer periphery of the cammodule comprising a groove, the first axis oriented in the groove. 24.The archery bow of claim 23, wherein a portion of the groove comprisesan arcuate surface.
 25. The archery bow of claim 23, wherein a portionof the groove is semicircular.
 26. The archery bow of claim 17, the cammodule comprising a rotation stop arranged to contact the power cable.27. The archery bow of claim 17, the cam module comprising a first cammodule that provides the archery bow with a first draw weight, the firstcam module detachable from the body and replaceable with a second cammodule, the second cam module providing the archery bow with a seconddraw weight.
 28. The archery bow of claim 27, the second cam modulecomprising a second module fastening location aperture the second cammodule attachable to the body in a first position, an intermediateposition and a last position, in the first position, the second modulefastening location aperture aligned with the first aperture, in theintermediate position, the second module fastening location aperturealigned with the intermediate aperture, in the last position, the secondmodule fastening location aperture aligned with the last aperture. 29.The archery bow of claim 17, the fastening location aperture comprisinga first fastening location aperture, the cam module comprising a secondfastening location aperture, when the first fastening location apertureis centered upon one of the apertures, the second fastening locationaperture is not centered upon one of the apertures.
 30. The archery bowof claim 17, the plurality of apertures comprising a first plurality ofapertures, the body comprising a second plurality of apertures alignedon an arc of constant radius from the first axis.
 31. The archery bow ofclaim 30, wherein the radius of the arc of the first plurality ofapertures is different from the radius of the arc of the secondplurality of apertures.
 32. The archery bow of claim 30, the fasteninglocation aperture comprising a first fastening location aperture, thecam module comprising a second fastening location aperture, the firstfastening location aperture aligned on the arc of the first plurality ofapertures, the second fastening location aperture aligned on the arc ofthe second plurality of apertures.